An NFA is represented formally by a 5-tuple, (Q, Σ, Δ, q0, F), consisting of
1. a finite set of states Q
2. a finite set of input symbols Σ
3. a transition function Δ : Q × Σ → 2Q
4. an initial (or start) state q0 ∈ Q
5. a set of states F distinguished as accepting (or final) states F ⊆ Q.